Checkerwork and brick therefor



.' 2 sheds-sheet -1 FIE T. H. KENNEDY GHECKERWORK AND BRICK THEREFOROct. 1 2, 1948.

Filed Aug. 10, 1945 Oct. 12, 194s. T. H. KENNEDY v 2,451,392

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Patented Oct. 12, 1948 CHECKERWORK AND BRICK THEREFOR Truman H. Kennedy,McKeesport, Pa., assignor to National Tube Company, a corporation of-New Jersey Application August 10, 1945, Serial No. 610,023

Claims.

The present invention relates to improvements in heat exchangingcheckerwork and more particularly to checkerwork and brick especiallyadapted for use in connection with hot blast stoves, such as are usedfor heating air for-blast furnaces.

Formerly, the sizes and shapes of bricks and the method of laying thebricks in blast furnace stoves, had been reduced to a common practice,and this practice was accepted by builders and operators as verysatisfactory under the then existing conditions. The size of firebrickcommonly used in such stoves was 10 long x 6" Wide x 2%" thick. Thebrickwork was laid in the pattern known as the basket weave, wherein thebricks came into close physical contact'with each other, and thefinished assembly became a closely bound and stable structure. Thevertical flues formed by this geometric basket weave design were 4"square and the vertical walls forming this flue opening never exceededthe thickness of one brick or 2 This flue area, of 16 square inches, wasdeemed necessary on account of the nature of the gas burned in thestove. At that time, the gas used for heating stoves was but partiallycleaned and contained much dust. Moreover, the effective brick mass orratio of effective brick mass to brick surface was relatively low andinefficient.

More recently, the practice of using raw dirty furnace gas to heat thestoves was discontinued. The gas is now thoroughly cleaned, to theextent that the gas used in a furnace stove is usually cleaner thanoutside atmospheric air. As a direct result of the elimination of dustfrom the gas, it is now the practice to construct the vertical flues inthe checkerwork at a much reduced cross-sectional area. An opening of 2"x 2" cross section, or its equivalent in square inches is favorablyconsidered by most builders and operators. It is naturally expected thata consequent reduction of the thickness of the brick to some dimensionsuch as 1 should follow the reduction of,

the flue area from '16 to 4 square inches. Assuming the brick has athickness of 1 A", the resultant length of this brick to form thefavorite basket weave design would be 5 /2" long. A brick having alength of only 5 would be entirely too short for practical use and doesnot find favor with builders and operators. As a result, designers andconstructors have evolved a variety of brick designs and especially newpatterns and con- 2 tive brick mass, are expensive to manufacture andare either fragile or unstable, or both.

It has also been proposed to use brick of substantially conventionalwidth and breadth but increased depth or thickness with an elongatedsi'ot therein which will provide a central vertical flue when suchbricks are superposed in cross-.

wise relation. This design permits laying the brick in basket weave withits attendant advantages and while the effective brick ratio is.

increased slightly over solid brick, the increase is so smallthat theincreased efliciency is notv enough to offset the increase in cost.Moreover, theflues insuch structure are of unequal size and do notprovide an even flow of air therethrough and, since the fines are not ofequal size, the ratio of flue surface to brick mass area is not constantand consequently undesirable.

Accordingly, it is an object of the present invention to provide abasket weave checkerwork having maximum heating surface per unit ofmass.

It is another object of the present invention to provide a multi-fluedbasket weave checkerwork that may be either columnar or crossbonded.

the checkerbrick of my invention;

Figure 2 is an elevation thereof;

Figure 3 is an isometric view of checkerwork laid in cross-bondedrelation;

Figure 4 is a section on line IV-IV of Fgure3 Figure 5 is a plan of amodified form of checkerbrick; and

Figure 6 is a similar view of a further modiflcation.

Referring more particularly to the drawings,

' the numeral 2 designates a refractory brick in structions to obtain amaximum area of heating the form of a rectangular parallelepiped throughwhich there is a central vertically extending opening or flue 4. Theflue .4 is'perpendicular to the planes or faces 8 of repose of the brickas laid to form checkerwork- At opposite ends of the brick 2 areopen-ended flues 6 which are parallel to the flue 4. 'An open sided flue10, normal to the flue 4, is provided in one of the faces 8 and.

extends thereacross intersecting the central flue 4.

The brick 2 is of substantial thickness to give individual brickstability and convenience of handling. The 'width l2 of the brick issuflicient to insure proper thickness of wall and is therefore dependenton the number of flues across the width of the brick. The length I 4 'ofthe brick 2 is directly dependent upon the dimension I 6 of the centralflue 4. The length I4 exceeds or is equal to the brick width l2 plustwice the dimension l6 across the internal flue, which is generallysubstantially square but may be circular or otherwise as desired. Thus,it follows that the open-ended flues 6 have substantially the same areaas the central flue d and may be of generally similar geometrical form.However, in the case of square openings, it is desirable that the endflues be heavily filleted in the form of a radius l8 to strengthen thecantilevered fins 20 against breakage in handling and to providestrength for supporting superposed brick to form checkerwork.

From the foregoing, it appears that by properly proportioning the wallthickness of the brick so that it is all usable as a heat exchangemedium, the brick mass is effectively used and due to the provision ofeffective flue surface or area that a high ratio of 95% or greater ofratio of brick mass to heating surface is obtained.

By reference to Figures 3 and 4 of the drawings, wherein fragmentaryviews of checkerwork composed of brick 2 are shown, it is seen that thebricks are laid in courses of a continuous longitudinal-lateral abutmentpattern forming the so-called basket weave. By reason of such coursesthe open-ended flues 6 are closed by being abutted against a verticalside of the adjacent brick. 1 Since the end flues 6 are closed by theabutted sides of the adjacent brick, relative shifting 'UJEI'COf willnot vary the flue area. In addition, due to the aforementioned length 14of the brick exceeding the width I! by twice the flue dimension Hi,there is formed centrally within each four bricks 2, in laid-upposition,

an additional free flue 22 having substantially the same area as theflues 4 and 6.

The superposed courses of brick as shown in Figures 3 and 4 may be laidin cross-bonded relation so that the superposed individual bricks are atright angles to each other with the central flues or openings 4 inalignment. By reason of such arrangement, it is noted that each centralflue 4 is connected to the end flues 6 of the abutting brick on eitherside. This provides alternating cross-draft to increase the heatingsurface and to serve as by-passes when either flues 4 or 6 becomecompletely or partially plug ed.

Such cross-bonded relation in checkerwork is particularly desirable inthe lower portion of a. hot blast stove since it provides the greatestpossible rigidity and strength. The ends of the brick being abuttedagainst the sides of the adjacent brick provide stability and resistanceto-tuming caused by the alternate heating and cooling of the checkerwork. If desired in the upper portion of the stove, the bricks maybe laid in columnar form, that is, with the superposed bricks invertical alignment, without afiecting the flue areas. This may bedesirable since such courses are easier to lay and permit maximum freevertical expansion in the hottest region of the stove.

In Figures and 6, I have shown modified forms of checkerbrick whichachieve the foregoing resuits and can be laid in basket weave in eithercross-bonded or columnar form. It is seen that in rows so that each rowhas the same number of flues-as the number of end flues. Due to thisspacing and arrangement, if a brick is superposed at right angles on abrick, the flues can be aligned in the same manner as the singlefiuedbrick. In this case, also a high ratio of heating surface per unit ofbrick mass is obtained, making such brick efficient to use. Also theyhave the same inherent stability of basket weave as is obtained by thesingle-flued brick.

While I have shown and described several speciflc embodiments of myinvention, it vwill be understood that these embodiments are merely forthe purpose of illustration and description and that various other formsmay be'devised within the scope of my invention, as defined in theappended claims.

I claim:

1. A checkerbrick comprising a refractory rectangular parallelepipedhaving at least one central vertical opening therethrough and anopenended flue on each end thereof in substantial alignment with saidcentral opening, said openended flue having substantially the same areaas said central opening, the length of said checkerbrick beingapproximately equal to the width plus twice the diameter of said centralopening.

2. A checkerbrick comprising a refractory rectangular parallelepipedhaving at least one central vertical opening therethrough and at leastone open-ended flue on each end thereof, each of said open-ended flueshaving substantially the same diameter as said central opening, thenumber of said central flues being the square of the number ofopen-ended flues on either end of said brick, said central flues beingso disposed that the flues in a superposed brick disposed at rightangles will be in alignment therewith.

3. Checkerwork comprising a plurality of courses of rectangular brick,each brick having a central vertical flue and open-ended vertical fluesat each end thereof, the alternate brick in a course being disposed atright angles to the intermediate brick to close said open-ended flues.

4. Checkerwork comprising a plurality of courses of rectangular brick,each brick having a central vertical flue and open-ended vertical fluesat each end thereof, the alternate brick in a course being disposed atright angles to each other to close said open-ended flues and formclosed vertical flues having substantially the same area as said centralflue.

5. Checkerwork comprising a plurality of courses of rectangular brick,each brick having a central vertical flue and open-ended vertical fluesat each end thereof, the alternate brick in a course being disposed atright angles to each other to close said open-ended flues byperpendicularly abutting the ends of said brick against the mid-portionof the adjacent side of the adiacent brick to form' closed verticalflues and to form vertical flues between the brick, said closed verticalflues and the flues formed between said brick having substantially thesame area as said central flue.

6. Checkerwork comprising a plurality of courses of rectangular brick,each brick having a central vertical flue, an Open-ended vertical I flueat each end thereof and a horizontal opensided flue extending acrosssaid vertical flue, the

' alternate brick in a course being disposed at right said horizontalflue.

7. Checkerwork comprising a plurality of courses of rectangular brick,each brick having a central vertical flue, an open-ended vertical flueat each end thereof and a horizontal opensided flue extending acrosssaid brick tointersect" said central flue, the alternate brick beingdisposed at right angles to each other to close said open-ended flues byperpendicularly abutting the ends of said brick against the mid-portionof the adjacent side of the adjacent brick and form vertical flueshaving substantially the same area as said central flue and superposedcourses being placed with vertically adjacent brick at right angles toeach other with the central flue aligned to connect said central fluewith the open-ended flue of the adjacent brick on either side thereof bysaid horizontalflue.

8. Checkerwork comprising a plurality of courses of rectangular brick,each brick having at least one vertical flue therethrough and at leastone open-ended vertical flue at each end thereof, the alternate brick ina course being disposed at right angles to each other to close saidopen-ended flues by abutting the ends of each brick against themid-portion of the adjacent side of the adjacent brick.

9. A checkerbrick comprising a refractory rectical flue therethrough andhaving at least one ber of said central flues being the square of thenumber of open-ended flues on either end thereof, said central fluesbeing so disposed that the flues in superposed right angularly disposedbricks will be in alignment, the side walls of said brick beingsubstantially flat whereby the openended flues of a right angularlydisposed brick in contact therewith will be closed by said flat sidewalls and form flues having substantially the same area as said centralflues.

10. A checkerbrick comprising a refractory rectangular parallelepipedhaving at least one vertical flue therethrough and having at least oneopen-ended flue on each end thereof, the

number of said central flues being the square of the number ofopen-endedflues on either end thereof, said central flues being sodisposed that the flues in superposed right angularly disposed brickswill be in alignment, the side walls of said will be closed by said flatside walls.

open-ended flue on each end thereof, the numfile of this patent:

TRUMAN H. 'KENNEDY.

REFERENCES CITED The following references are of record in the UNITEDSTATES PATENTS Number Name Date 659,602 Bredel Oct. 9, 1900 1,319,113Reagan Oct. 21, 1919 1,902,348 Wagstafl Mar. 21, 1933 2,185,559 Mohr,Jr., et al. Jan. 2, 1940 2,192,723 Whitacre Mar. 5, 1940 2,205,419Kraemer June 25, 1940 FOREIGN PATENTS Number Country Date 9,392 EnglandJune 25, 1884 680,458

France May 1, 1930

